This invention relates in a preferred embodiment to a method and apparatus for treating a plurality of zones of a processing line with a carrier liquid, the liquid including a lubricant and additional ingredients. One particular application of the invention is in the distribution of a lubricant composition to surfaces which require lubrication and more particularly the distribution of lubricant composition to conveyors or tracks along which bottles or cans are conveyed.
In canning and bottling lines large numbers of cans or bottles are conventionally transported using variously designed conveyor systems. The cans or bottles slide along these conveyors and it is necessary to supply the conveyors with a lubricating material to reduce friction and to afford some cleaning action. Such materials are usually water soluble or water dispersible and may comprise active lubricating agents such as soap and optionally other components such as detergents, solvents and water softening and conditioning agents. Typically the carrier liquid is water which has been treated with chelates and bactericides. To be effective, such additives must be maintained at specific, minimal concentrations regardless of particular concentration being used for the lubricating additive.
Canning and bottling lines typically have many conveyor tracks in a conveyor system and the lubricant is diluted and applied to the various tracks in the system by spray, foam or drip application, the spray nozzles or other outlets being fed by a pipework system from a central point. At the central point, there is typically a dilution device which takes neat chemical product and dilutes it with the carrier liquid i.e., water in most cases. The resulting solution is pumped through the pipework system to the points of application. The thin watery lubricating composition is customarily pumped or sprayed onto the various conveyor tracks at a variety of selected locations.
The lubricating compositions previously used and most lubricating systems accomplish more than simply lubricating the conveyor. For example, in the beer brewing industry, the growth of bacteria on the conveyor is a problem. It has been customary in the past that the lubricating compositions sprayed onto the conveyor also include a bactericide for inhibiting bacteria growth. Similarly, the water supply in certain parts of the country has a relatively high mineral content. When such a water supply is used in the lubricating composition, it tends to rust or otherwise degrade the conveying apparatus. Thus, the lubricating composition also desirably contains a water conditioner and/or rust inhibitor. Other ingredients may also be included. Consequently, the lubricating composition which is conventionally sprayed onto the conveyors actually comprises a multiple-ingredient composition.
One prior art conveyor lubricating system is known as the Monarch Crown Lube System which is used by the Monarch Chemical Division of H. B. Fuller Company, the assignee of the present invention. In this system, a pump is provided for pumping a concentrate of the composition to a holding tank. This concentrate is then diluted with water to form the lubricating composition. The lubricating composition contained in the holding tank is then suitably applied to the conveyor. Operation of the pump for pumping the composition to the holding tank is controlled by a conductivity sensor in the holding tank.
Another system is disclosed in U.S. Pat. No. 4,262,776 to Wilson and Barrett. That patent is also assigned to H. B. Fuller Company, the assignee of the present invention. In this system, the ingredients which comprise the lubricating composition are supplied separately when formulating the composition by means of individual supply tanks in which a concentrate of each of the needed ingredients is held. Separate pumps are provided for separately conducting each of the ingredient concentrates to a holding tank. By varying pumping ratios the amount of any given ingredient in the final lubricating composition can be changed.
Another system has been disclosed in European Pat. Application No. 0079152 (Chemed Corporation). That application discloses an arrangement in which the lubricant and water are piped separately to points along a conveyor. This system allows the lubricant to be individually metered at each point as the lubricant and water are not mixed in the pipework itself.
Another system is disclosed in U.S. Pat. No. 4,627,457 to Bird, Cross and Singh. That patent describes a method of treating a plurality of zones of a processing line with a liquid comprised of a treatment liquid and a carrier liquid wherein the treatment liquid is introduced into pipes conveying the carrier liquid to each zone as discrete slugs and wherein the volume of each slug is selectively variable or wherein each slug may be introduced into the pipes at a selectively variable frequency.
One of the earlier problems with prior art lubricating systems was that the lubricating composition concentrate contained predetermined ratios of the various ingredients therein. The problem was that a single formulation of the concentrate was seldom effective for all conveyor plant operations. For example, a particular conveying application might have a serious bacteria growth problem. This might require that the composition being used in that application contain a high level of bactericide. This adjustment might be made by increasing the amount of bactericide concentrate in the lubricating composition. However, because of the ratio of the bactericide in any given concentrate was always fixed relative to the levels of the lubricant or the water conditioner, increasing the amount of the bactericide and the composition also increased the amount of lubricant being used and also the amount of water conditioner used. Thus, the amount of lubricant when increased might be to a point of excess such that it was unnecessarily costly and wasteful.
As an example, certain parts of a canning or bottling track need more lubricating and cleaning than others. In particular, in a bottling line which uses bottles which have already been used and are returned dirty by the user, the bottles at the in-feed-end of the line have a large amount of soil on them which tends to be transferred to the track. Also, there is liable to be spillage of the product with which the bottles or cans are being filled at the filling station, and the spilled product ends up on the track. Accordingly, additional lubrication is desirable at the filling station and separately at the dirty bottle in-feed. Since the lubricant is typically a soap-like chemical, over lubrication leads to excessive foaming. Excess foam is detrimental, for example, because it can trigger off optical scanning instruments and if spilled on the floor can lead to a safety hazard. Further, over lubrication is expensive because lubricant is wasted. The main constituent of the track lubricant i.e., the soap or the like precipitates lime soaps in the presence of hard water i.e., when mixed with hard water in the diluting system. These precipitates block the spraying nozzles and are generally detrimental to the operation. To overcome this problem, it is known to add a sequestering agent to stop precipitation. However, this sequesterant is typically an expensive chemical.
Consequently, attempts have been made in the prior art as evident by the above referenced patents to allow individual control over the concentrations of the various ingredients in the carrier liquid for use at different points in a processing line. As can be seen from the above referenced patents, various approaches have been made to solve this problem primarily by supplying the various ingredients of the lubricating composition separately to the carrier liquid. However, none of the prior art solutions to the problem have been completely satisfactory in that they tended to be overly complicated. Thus, it is a primary objective of the present invention to provide a new and improved apparatus wherein water conditioning and sanitizing ingredients and any other ingredients may be maintained at proper concentrations while the lubricant or other ingredient concentration is varied as desired in a simple straight forward manner.